Comminutor base seal



y 5 J.- J. WIRTS 2,375,455

.GOMMINUTOR BASE SEAL Filed Aug. 16, 1943 .in whole or in part.

' cutting zone.

render their use, objectionable. h 1 In accordance with thefipre fent;invention'I.

Patented May 8, 1945" Jdiuiy JQwirts, oleyela a, Ohio, ss gm to Chica'go Pump'Cornpany, a corporation' ofDela- Ware This invention relates to comminuting devices of the rotary screen type and more particularly to improvements in the seal between the comminutor base and the rotary screen for preventing solids from by-passing the cutting zone of said device.

Comminuting devicesin accordance Withthe present invention are usually installedjin a basin which forms a part of the raw sewage channel.

Pieces of wood, paper, rags, long stringy. material and other solids carried by the sewage are strained therefrom by .the rotary screen and are then comminuted at a cutting zone by the coaction of relatively moving cutting members.

The small comminuted particles pass through the screenwith the sewage liquor to-the downhave devised a seal'whichis free from the fore- {going objections in that it is not subjected to the stream channel, which may lead the sewage to l .a place for further treatment asis well-understood in the art. Some of the solids in the sewage entering the basin immediately pass-to the cutting zone and are there comminuted either along with recirculated partially comminuted solids are carried by the sewage liquor onto the,

. screen which, in turn, carries the solids to the As this" process continues the solids are comminuted to the desired size and pass through the screen to the downstream channel. 3

'In' order to prevent the solids from passing under the screen and thereby by-pass the cut ting zone, the space between thebottom of the rotary screen and the comminutor base. was

bridged by a seal. This seal usually consisted of a strip of flexible material made from'a waterand oil-resistant material such. as; Neoprene,

having one edge. fixedly. secured to the comminutor base and the other edge in frictional engagement with the outer wall] of the rotary screen at the bottom thereof; Because of the excessive wear onthe seal material due to the rubbing action of the rotary screen and the ab-' ra'sive' action of the gritin the sewage, the seal had to be replaced frequently, thereby resulting in excessive maintenance costs. In addition, the rubbing action of the seal material on the rot/ating screen, augmented by theabrasive action of The. remainder of the solids 1 rubbingfaction of the rotating screen and hence a .is not subjected to. excessive wear, and which may be madeof relatively inexpensive, relatively" non-critical materials such as plastics, metals, etc} Moreoventhe seal is simple in-design and construction and relatively inexpensive to manufacture, I a .The seal of vthe present invention does not actually bridge the .gap between the bot-tomof therotary screen and the base of. the comminuting device, but rather, it forms a-lsmall chamber,

having an entrance of restricted size, which 'ex tends completely about the gapxandthe exposedportion of the rotaryscreen, at and slightlyy above the lower extremity thereof. The entrance to the chamber is of a size to permit partially and completely comminuted solids and; particularly,. .uncomminuted or insufficiently comminuted stringy material ,to pass into the.

chamber .with the sewage; .Ihese solids are then carried by the sewage against the screen and, in turn, by the screento thecutting zone where they are comminuted. The seal of the present invention serves, in efiect,fto trap solids tending to by-pass the screen'and to insure that these solids, particularly .long stringy solids, are

minuted before being carried to the downstream channel;

- The 'present invention is illustrated in the accompanying drawing inconjunction with 31,131'8 ferred form of drum-screen type or comminuting device, shown-and described in-detail in the the grit, deleteriously affectedthe screem gAlso, v

andparticularly at the present time,,the rubberlike'materials from whicn'thelsesems w remad are not readily available'for purposes not; directly connected with the .war effert. I 'l e foregoing and other disadvantages of these priorart seals patent to Corson W;. Chas e,.2,322,'922, granted June'29', 1943', andjit-isto be understood that it is not to be construed as'limited for use with that v form of device since it iscapableof usein connectionwith-all types of rotary screen comminuting-devices. I

The invention Fig. 2 is a horizontal section, taken substan- -tially along the line 2-4! of Fig. 1, showingiurther'details of theseal; and I i l I Fig-3 is an enlarged detail section of the seal I takenqaleng theline3- 3 of Fig. 2;, i

Referring to the drawingthe comminutingicle vice :there shown is of therotary' drum screen 'typeandcomprises aibase N of -annular. .sh;ape, v

Will be readilyunderstood from the following description taken in conjunction with the accompanying drawing, in which:

' Figure 1 is a perspectiveview. of a preferred. .form-ofKcomminuting device, with parts broken away and in section to show the details of the sealin accordance with the present invention;

base to the downstream channel.

; astandard I2 mounted thereon, a head M mounted on the standard, a motor 16 mounted on the head and a screen l8. 'I'hescreen is of substan- I I tially cylindrical form, extending from the head to a position slightly above the top' of the base, and is mounted for rotation on ashaft I9 (Fig, 2) which is driven bylthe motor. It will benotedthatthe inner periphery of the screen is aligned with th'e inner periphery of the annular,- shaped base, thereby providing a space or gap 20 betweenthe relatively moving parts disposed at right anglesto the space or opening 22. de-

downstream .channeL.

The screen shown in the drawing form of 'a *casting having an outer cylindrical wall and comminuted solids may'pass into the interior of the screen'and, ultimately,-to the downstream from the screen, as desired. These teeth and shear bars coast with the teeth on the stationary cutting combs32, which are mounted on standard 12 adjacent the screen, to comminute solids.

f muse, the comminuting device is positioned within a basin into whicha stream containing solids, such asaraw sewage stream, is introduced.

The liquid and smaller solids pass through the screen and fall through the opening 22 in the The larger solids are intercepted by the screen and are carcomminuted to a size small enough-so that they can pass through the screen along with the sewage. liqu Mounted on base {in is a sutstannan v ringcourse, overlap a Seal 34 forms a chamber 44 which extends about gap 20 and thelower extremity of the Screen. Theentrance' to the chamber is the clearance space 40 and the ,exit therefrom is gap 20. The exitfrom thechamber is not aligned'with the entrance thereto; in the form shown it is at right angles thereto, and this, in'effect, forms 7 somewhat of a labyrinth arrangement which does finedby the base which communicatesiwi'th the [which .is provided with a plurality of series of horizontal slots 24, each series being separated V by solid wall portions 26, through which the liquid,

ried thereby to the cutting combswhere' they are shaped memberior sea1 34,,of metal or other uitable mama, having. a substantially Z-shaped section, which extends entirely. about gap 20 and the lower extremity 'of the -screen except, for the spaceoccupied by standard [2. Seal 34 is provided with a cut-out to enable it to straddle the standard. The lower leg portion 36 of the seal is provided with anopening through which "a bolt is threaded into the base tov securetheseal thereo to. The upperl'eg portion 38 is in-turned towards the screen and the free edge thereof terminates sufliciently far from-the screen to allow for ample clearance for the projectingcutting teeth 28. For

most types and sizes of comminuting devices a clearance space referred to by the numeral 40, in they order of about /;",is sufiicient for this purpose. Obviously, the size of this space may be varied to meet any'particular requirements. The intermediate, vertically disposed 'Web por tion 32-0f the sealjmay varyyratherwidely in height although a is essential thatit be of sufdetails'are not to beconsidered as, limitations upon the invention described; j Whether the chamber-forming'portion of the :seal is ;of the ficient height to overlap some of the cutting elements on the rotating'screen'.

For practical effectiveness in securing the desired comminution ,of the solids, particularly stringy solids, entering clearance space 40, web 42 should at least b of a height to overlap the first'two, rows'ofvslots above the bottom of the screen, although I prefer that it be of a height to loverlap three or four rows oislots. It may, of

not [favor the flow of liquid and solids suspended therein from chamber M directly to the exit as against the desired flow from the chambertothe slotsin the screen.-

In the operation of; the comminuting device in v' accordance with the present invention, the raw 'sewagestre'am or other liquid stream containing,

solids flows into the basin containing the coinmi'nutin deviceand the liquid and smaller solids pass throughthe screen slots to the -downstream channel? Thein'tercepted solids are carried by 1 the screen to the cutting zone and are there comminuted to a size so that they can pass through the slots. Some of the smaller solids and some of the uncomminuted or partially comminuted stringy solids may pass alongwith the liquid through clearance space 40 into chamber and;

from'there most, if not alLof the liquid and solids will flow towards thei'screen; "The liquid and smaller solids will pass through the slots surrounded by the sear but theinterceptedjsolids will becarried by the screen to the cutting zone where they will-be comminu'ted -to' a size sufiicientlysmall to enable them to pass through the slots. F

It'is' apparent frorn the fo egoing that with the seal of 1 the present invention thereris provided a charhber'or trap for partially comminuted solids, particularly stringy solids, which might otherwise by-pass' the screen and the cutting zone by f passing through the usual clear- 'ance space between the 'lower edge oi [the screen and the based from which the solids flow" to the screen and to the cutting zone for'come minution. f Some long stringy; solids entering chamberl i may passdirectly through gap 20;

however, this will take place only. occasionally, I if it take 'place at'all since the difierencein.

head between the interior of the screen and the chamber surrounding the screen, coupled with the labyrinth arrangement of the exit from the chamber, favors the flow of'liquid and suspended solids from the Chamber'thr ugh the'screen.

The details as to shapefanddimensionsof the sealgof the present invention may, otcourse, be varied in a manner readily apparent. toa skilled worker in the 'a'rt without departing item the 'scopeioff't'he appended claims, and hence these shape and form shown and described, or is other 'wi'se'shaped and positioned tojform the desired chamber and 'thenefcessary,clearance space is im material, but I prefer the former? l I clainiz 7 1Q The combinationfwitha comminuting device of "the rotary screen" type comprising a rotatable screen nds stationary base arranged toprovide a space'between the base andthelower extremity r a of the screen to allow forrelative rotation between said screen ;and base and wherein cutting v elements are provided'on said screen substan-f greater numberof rows of slots a but this is not'essential and ay even be objectionable since the capacity of the screen may 'thereby'be unduly-reduced.

tially throughout the length thereof and wherein stationary cutting elements are positioned adjacent the screen and extend throughout the length thereof to coact with the rotatable cutting elements to comminute solids, of a stationary member secured to the base and extending upwardly therefrom above the lower portion of the screen to over-lap at least some of the cutting elements on the screen, said 'member forming with the said base and the lower portion of the said screen a chamber which substantially surrounds the said space and the said lower portion of the screen, the upper extremity of said member being spaced from said screen to allow for clearance between the rotatable cutting elements and the said member, said last-named space forming an entrance to said chamber and the said first-named space an exit therefrom.

2. The combination with a comminuting device of the rotary screen type comprising a rotatable screen and a stationary base arranged to provide a space between the base and the lower extremity of the screen to allow for relative rotation between said screen and :base and wherein cutting elements are provided on said screen substantially throughout the length thereof and wherein stationary cutting elements are positioned adjacent the screen and extend throughout the length thereof to coact with the rotatable cutting elements to comminute solids, of a rigid stationary member secured to said base and extending upwardly therefrom above the lower portion of the screen to over lap at least some of the cutting elements on the screen, said member forming with the said base and the lower portion of the said screen a chamber which substantially surrounds the said base and the said lower portion of the screen, the said space forming an exit from said chamber and the upper free extremity of said member being spaced from said screen to allow for clearance between the rotatable cutting elements and the said member and to provide an entrance to said chamber.-

3. The combination with a comminuting device of the rotary screen type comprising a rotatable screen and a stationary base arranged "tive rotation between said screen and base and bers.

to provide a space between the base and the lower extremity of the screen to allow for relawherein cutting elements are provided on said screen are positioned adjacent the screen and extend throughout the length thereof to coact with the rotatable cutting elements to comminute solids, of a rigid stationary member secured to said base and extending upwardly therefrom above the lower portion of the screen to over-lap at least some of the cutting elements on the screen, said member forming with the said base and the lower portion of the said screen a chamber which substantially surrounds the said base and the said lower portion of the screen, the said space forming an exit from said chamber and the upper free extremity of said member being spaced from said screen to allow for clearance between the rotatable cutting elements and the said member and to provide an entrance to said cham-' ber of more restricted dimensions than said chamber. 7

4.'A comminuting device of the rotary screen type comprising a rotatable screen and a stationary base arranged to provide a space between the base and the lower extremity of the screen to allow for relative rotation between said screen and base, said screen having cutting elements thereon substantially throughout the JOHN J. wm'rs.

substantially throughout the length thereof and wherein stationary cutting elements 

